System Description

In the medium speed range, the power valves are closed. Under this condition, the pressure waves of exhaust stroke do not disturb those of intake stroke of each opposite bank. Therefore, charging efficiency is increased together with the effect of the long intake passage.

On the other hand, in the high speed range, the power valves are open. Under this condition, the pressure waves of intake stroke are resonant with those of each opposite bank exhaust stroke. Therefore, charging efficiency is also increased.

In addition, both valves 1 and 2 are controlled to be open or closed in other ranges mentioned above. Thus the maximum charging efficiency is obtained for the various driving conditions.